It is known that ultraviolet ("UV") light in the germicidal range, of approximately 254 nm, can be used to disinfect water, that is, to rid water of bacteria, viruses, algae and so forth. Known prior water purification systems that use UV light are large, installed systems that each include a flow-through subsystem, which causes water to travel past an elongated UV light source that is suspended therein. A quartz sleeve surrounds the UV light source, to protect it and its electrical connections from the water while allowing the UV radiation to pass to the water. Such systems are currently used to purify water for use in, for example, hospitals or schools.
The flow-through subsystems each essentially include a flow-through chamber, i.e., a pipe. As water flows through the pipe, it travels past the quartz sleeve, and thus, the UV light source, and is exposed to UV radiation. The UV radiation kills the bacteria, viruses and so forth that are present in the water. Waste byproducts may build up on the quartz sleeve, and accordingly, the systems include wiper mechanisms that periodically clean the quartz sleeves. These systems typically include a mechanism, such as a viewing port and/or a sensor, for determining the output level of the lamp. A user can visually check the lamp through the view port to ensure both that the lamp is turned on and that the quartz sleeve is sufficiently clean to pass the level of UV radiation required to disinfect the water. The sensor measures the UV radiation for the same purpose,
These flow-through systems work well for disinfecting relatively large quantities of water. They are not, however, suitable for disinfecting small quantities of water.
Today campers, hikers, travelers and the like encounter bacteria and virus infected water in streams, lakes and rivers, and in some countries even in the local plumbing. These hikers, campers and travelers must thus either carry bottled water with them or use portable filtering systems and/or chlorine, hydrogen peroxide or iodine tablets, to disinfect the water. The filtering systems are generally bulky, and thus, inconvenient to carry. Further, while they may remove bacteria and algae from the water, they do not remove viruses, which are typically too small to be caught in the filters. The chemical tablets are certainly portable but they are relatively expensive. Further, the tablets change the taste and smell of the water and add undesirable chemical byproducts to the water. Indeed, the tablet manufacturers generally warn against continuous use of the tablets, for health reasons.